When contacted she initially suggested the letter - which includes her signature - was a fake. She now accepts it was genuine.
“Never has a prime minister wielded so much power, made so little effective use of it and been seen to be in quite such an indecent haste to blow his own trumpet."
Karl Turner MP said the prime minister is "utterly unfit for office" after watching the clip.
"The Johnson family ethos: the crime is getting caught out, not the actual act."
By Nicholas Janni.
George Eustice said Johnson's Savile comments came "in the heat of the moment".
Truth has been "optional" in Boris Johnson's government, Sir John said in a fiery speech.
"The PM knew exactly what he was doing," Starmer said.
For vulnerable people, 'Freedom Day' is "a bit hollow", a health charity worker said.